Re: [PATCH v2] revision.c: really honor --first-parent

>>  - My original patch did just that, it simplified the code to make sure
>>   that all other parents beside the first parent are ignored when
>>   walking the tree.
>
> Except for the case where the first parent had been already SEEN; then
> it would continue to test the next parents until one was found which
> was not already SEEN and _that_ parent would be treated as if it was
> first. And as Nanako showed, a simple `git rev-list HEAD^..HEAD` marks
> both HEAD and HEAD^ as seen. When combined with --first-parent, the
> result (with your patch) is that HEAD^2 is treated as the first
> parent. With my patch on top of yours, the walk stops as HEAD^, which
> is what we probably both want.
>
>>  - Your code now doesn't simplify the (IMO) convoluted walk, and still
>>   marks things as seen, even though in the first-parent case, these
>>   commits are not really seen at all.  It implies that your code
>>   generates differing output, depending on the merges present.
>
> I don't think so. My code should neither follow nor mark as SEEN any
> parent but the first (but I could obviously be wrong).